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SUGAR  AND  SUGAR-MAKING 


BY 

JAMES  B.  McNAIR 

Assistant  Curator  of  Economic  Botany 


Botany 
Leaflet  13 


FIELD  MUSEUM  OF  NATURAL  HISTORY 

CHICAGO 
1927 


J 


LIST  OF  BOTANICAL  LEAFLETS  ISSUED  TO  DATE 

No.    1.  Figs $  .10 

No.    2.  The  Coco  Palm 10 

No.    3.  Wheat 10 

No.    4.  Cacao        10 

No.    5.  A  Fossil  Flower 10 

No.    6.  The  Cannon  Ball  Tree 10 

No.    7.  Spring  Wild  Flowers 25 

No.    8.  Spring  and  Early  Summer  Wild  Flowers      .     .        .25 

No.    9.  Summer  Wild  Flowers 25 

No.  10.  Autumn  Flowers  and  Fruits 25 

No.  11.  Common  Trees 25 

No.  12.  Poison  Ivy 25 

No.  13.  Sugar  and  Sugar- Making 60 

D.  C.  DAVIES.  Director 


FIELD  MUSEUM  OF  NATURAL  HISTORY 
CHICAGO,  U.S.A. 


Courtesy  of  the  United  Fruit  Co. 

SIXTEEN  SUGAR  CANES  FROM  ONE  SEED  IN  CUBA. 


Field  Museum  of  Natural  History 

DEPARTMENT  OF  BOTANY 
Chicago.  1927 

Leaflet  Number  13 

Sugar  and  Sugar-Making 

Sugar  is  manufactured  by  plants  for  their  own 
use.  It  is  formed  in  their  green  parts  from  carbon 
dioxide  of  the  air  and  the  water  of  the  sap.  Under  the 
influence  of  sunlight  filtered  by  the  green  coloring 
matter  (chlorophyll)  of  the  plant,  the  gas  and  water 
combine  to  form  formaldehyde  which  is  later  con- 
verted into  glucose  and  other  sugars. 

Sugar  is  soluble  in  the  plant  sap  and  is  carried  in 
the  sap  to  various  parts  of  the  plant  to  be  transformed 
where  needed  into  other  substances  such  as  fiber. 
Some  plants  store  sugar  for  future  use,  e.  g.,  for  the 
growth  and  seed-production  of  the  following  year,  as 
is  the  case  with  the  sugar  beet. 

For  storage,  particles  of  sugar  may  unite  with 
each  other  to  form  larger,  less  soluble  bodies  such  as 
starch  due  to  the  union  of  glucose  with  glucose  in 
potatoes,  the  starchlike  substance  inulin  from  the  sugar 
levulose  with  levulose  in  dahlia  tubers,  cherry  tree  gum 
from  the  sugar  arabinose  with  arabinose  in  cherry 
trees,  and  gum  arabic  from  the  sugar  galactose,  arabi- 
nose, and  arabinon  in  acacia  trees. 

Sugar  may  also  join  with  other  substances  in 
plants  as  when  glucose  unites  with  gallic  acid  to  form 
tannin  in  the  oaks  and  sumacs,  rhamnose  with  fisetin 
to  form  the  dye  stuff  fustic  in  the  smoke-wood  tree 
(Rhus  Cotinus),  and  mannose  with  cellulose  to  form 

[181] 


2  Field  Museum  of  Natural  History 

"vegetable  ivory"  in  the  kernel  of  the  ivory  palm 
(Phytelephas  macrocarpa).  Sometimes  these  com- 
pounds are  poisonous  as  in  the  cases  of  arbutin  and 
amygdalin.  Arbutin  is  found  in  the  trailing  arbutus 
and  bearberry,  while  amygdalin  is  found  in  the  seeds 
of  the  bitter  almond,  apricot,  and  peach. 

Besides  its  use  as  food  for  the  plant,  sugar  manu- 
factured by  plants  also  serves  a  useful  purpose  in  the 
nectar  of  flowers  by  attracting  insects  for  pollination 
and  in  fruits  by  making  these  attractive  to  animals 
that  aid  in  seed  dissemination.  Nectar  contains  for  the 
most  part  cane  sugar,  glucose,  and  levulose,  and  is 
taken  by  bees  to  form  honey.  Some  flowers  contain 
sufficient  nectar  to  be  attractive  to  man  as  a  source  of 
sugar.  Among  these  are  those  of  the  Madhuca  tree 
(Madhuca  latifolia),  the  Honey  Flower  (Melianthus 
major),  and  the  Boer  Honey  Pots  (Protea  mellifera 
and  Protea  cynaroides) .  W.  Ferguson  says  that  in  the 
time  of  Manu,  about  4,000  years  ago,  the  Hindus  knew 
how  to  make  sugar  from  the  flowers  of  the  Madhuca 
tree.  The  natives  of  Cape  Colony  collect  the  Honey 
Flowers  for  the  large  quantity  of  sugar  they  contain, 
and  the  Boers  of  South  Africa  make  use  of  the  Honey 
Pot  flowers  for  the  same  purpose. 

Many  different  sugars  occur  in  nature  in  plants 
and  animals.  Other  sugars  not  yet  found  in  nature 
are  produced  synthetically  in  the  laboratory.  The  gen- 
eral term  "sugar"  applies  to  a  large  number  of  sub- 
stances composed  of  three  elements,  carbon,  hydrogen, 
and  oxygen  combined  in  certain  proportions.  Sugars 
which  possess  distinct  chemical  and  physical  prop- 
erties are  distinguished  by  special  names,  e.  g.,  sucrose. 
The  sugars  belong  to  a  much  larger  group  of  sub- 
stances called  carbohydrates,  most  of  which  conform  to 
the  general  formula  Cm  (H20)„,  where  m  and  n  stand 
for  various  multiples.     See  outline  on  page  4.     The 

[  182  ] 


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Sugar  and  Sugar-Making  5 

other  plant  substances  of  this  group,  cellulose,  starch, 
and  gum,  are  more  complex  but  may  be  decomposed 
or  broken  down  into  various  sugars. 

Commercial  sugars  are  named  after  the  particular 
plants  from  which  they  are  extracted,  for  instance, 
cane,  beet,  maple,  sorghum,  palm.  The  chief  con- 
stituent of  all  these  is  a  single  substance — sucrose  or 
saccharose.  Corn  and  grape  sugar  on  the  contrary 
consist  of  another  chemical  substance — glucose. 

All  sugars  are  not  of  equal  sweetness.  Corn  sugar 
(glucose)  is  only  three-fifths  as  sweet  as  cane  sugar, 
while  levulose  is  about  equal  to  cane  sugar  in  sweet- 
ness. 

CANE  SUGAR 

The  sugar  cane  (Saccharum,  officinale)  belongs  to 
the  grass  family  (Gramineae)  which  includes  wheat, 
oats,  corn1  (maize) ,  sorghum,  etc. ;  but  the  sugar  cane 
towers  above  most  of  them,  sometimes  attaining  a 
height  of  twenty  feet.  Its  native  country  is  Southern 
or  Southeastern  Asia.  Being  a  plant  of  the  moist 
tropics  and  subtropics,  it  grows  successfully  only 
where  the  average  temperature  does  not  fall  much  be- 
low 80°  Fahrenheit  nor  the  rain  below  sixty  inches  a 
year. 

History. — Various  classical  writers  of  the  first  cen- 
tury noticed  the  sweet  sap  of  the  Indian  honey-bearing 
reed  or  its  granulated  saltlike  product.  This  product 
was  imported  to  Europe  from  India  and  from  Arabia 
and  Opone  (these  being  entrepots  of  Indian  trade)  un- 
der the  name  of  saccharum  (<janxa.pi  from  Sanskrit 
sarkara,  gravel,  sugar),  for  medical  use. 

Before  the  Middle  Ages  Europeans  had  no  clear 
idea  of  the  origin  of  cane  sugar.     It  was  confounded 

'The  Aztecs  in  Mexico  made  use  of  the  corn  plant  for  sugar 
in  the  same  manner  as  sugar  cane  is  used  now. 

[185] 


6  Field  Museum  of  Natural  History 

with  manna  or  was  thought  to  exude  from  the  stem  of 
a  plant,  on  which  it  dried  into  a  kind  of  gum.  The  art 
of  boiling  sugar  was  known  in  Gangetic  India,  from 
which  it  was  carried  to  China  in  the  first  half  of  the 
seventh  century ;  but  sugar  refining  cannot  have  been 
known  then,  for  the  Chinese  learned  the  use  of  ashes 
for  this  purpose  only  in  the  Mongol  period  (600  A.  D.) , 
from  Egyptian  visitors.  The  cultivation  of  the  cane 
in  the  West  spread  from  Khuzistan  in  Persia.  At 
Gunde-Shapur  in  this  region  "sugar  was  prepared 
with  art"  about  the  time  of  the  Arab  conquest,  and 
its  manufacture  on  a  large  scale  was  carried  on  at 
Shuster,  Sus,  and  Askar-Mokram  throughout  the 
Middle  Ages.  It  has  been  plausibly  conjectured  that 
the  art  of  sugar  refining,  which  the  farther  East 
learned  from  the  Arabs,  was  developed  by  the  famous 
physicians  of  this  region,  in  whose  pharmacopoeia 
sugar  had  an  important  place.  Under  the  Arabs,  the 
growth  and  manufacture  of  the  cane  spread  far  and 
wide,  from  India  to  Sus  in  Morocco,  and  was  also  in- 
troduced in  Sicily  and  Andalusia. 

In  the  age  of  discovery,  the  Portuguese  and  Span- 
iards became  the  great  disseminators  of  the  cultiva- 
tion of  sugar;  the  cane  was  planted  in  Madeira  in 
1420;  it  was  carried  to  San  Domingo  in  1494;  and  it 
spread  over  and  occupied  portions  of  the  West  Indies 
and  South  America  early  in  the  sixteenth  century. 
Within  the  first  twenty  years  of  the  sixteenth  century 
the  sugar  trade  of  San  Domingo  expanded  with  great 
rapidity,  and  it  was  from  the  dues  levied  on  the  im- 
ports brought  thence  to  Spain  that  Charles  V  obtained 
funds  for  his  palace-building  at  Madrid  and  Toledo. 

In  the  Middle  Ages,  Venice  was  the  great  Europe- 
an center  of  the  sugar  trade,  and  toward  the  end  of  the 
fifteenth  century  a  Venetian  citizen  received  a  reward 
of  100,000  crowns  for  the  invention  of  the  art  of  mak- 

[186] 


8  Field  Museum  of  Natural  History 

ing  loaf  sugar.  One  of  the  earliest  references  to  sugar 
in  Great  Britain  is  that  of  100,000  pounds  of  sugar 
being  shipped  to  London  in  1319  by  Tomasso  Lore- 
dano,  merchant  of  Venice,  to  be  exchanged  for  wool. 
In  the  same  year  there  appears  in  the  accounts  of  the 
Chamberlain  of  Scotland  a  payment  at  the  rate  of 
Is  9*4^  per  pound  for  sugar.  Throughout  Europe  it 
continued  to  be  a  costly  luxury  and  article  of  medicine 
only,  till  the  increasing  use  of  tea  and  coffee  in  the 
eighteenth  century  brought  it  into  the  list  of  prin- 
cipal food  staples.  The  increase  in  the  consumption  is 
exemplified  by  the  fact  that,  while  in  1700  the  amount 
used  in  Great  Britain  was  10,000  tons,  in  1800  it  had 
risen  to  150,000  tons,  and  in  1885  the  total  quantity 
used  was  almost  1,100,000  tons.  In  1924-25  the 
United  States  produced  88,483  of  a  world-production 
of  17,649,000  short  tons. 

Sugar  cane  was  introduced  into  Louisiana  from 
San  Domingo  by  the  Jesuits  in  1751.  Dubeuil  built  the 
first  cane-mill,  and  his  efforts  at  manufacture  failed. 
The  first  refined  sugar  was  made  by  Antonio  Mendez 
in  1792,  but  the  first  refined  sugar  on  a  commercial 
scale  was  made  in  1794  by  Etienne  de  Bore.  The 
plantations  of  these  two  planters  now  form  part  of 
the  city  of  New  Orleans. 

The  manufacture  of  sugar  was  very  crude  up  to 
1700.  Inefficient  mills  operated  by  wind,  water,  or 
oxen  were  used  for  extraction  with  lime,  clay,  and 
ashes  as  purifying  agents;  the  evaporation  was  ef- 
fected in  open  copper  or  iron  pans  placed  directly  over 
the  fire,  and  the  refining  consisted  in  melting,  boiling, 
and  recrystallizing.  These  crude  methods  still  exist 
in  some  countries,  especially  in  districts  where  cane 
is  grown  for  making    syrup  and  very  crude  sugar. 

Extraction. — There  are  in  practice  two  methods 
of  extracting  the  sugar  from  cane,  namely,  milling 

[188] 


Sugar  and  Sugar-Making  9 

and  diffusion.  The  older  and  more  generally  used  is 
milling,  the  diffusion  being  confined  almost  entirely  to 
manufacture  of  sugar  from  beets.  A  mill  may  consist 
of  two  or  three  rollers,  usually  placed  horizontally  and 
varying  in  length  from  eighteen  to  seventy-two  inches, 
and  in  diameter  from  twelve  to  thirty-two  inches.  If 
the  mill  is  to  be  operated  by  oxen  or  by  horses  the 
rollers  are  set  in  an  upright  position.  The  most  primi- 
tive mill  was  the  wooden  roller.  This  has  been  used 
in  a  small  way  in  some  of  the  southern  states  since 
the  Civil  War,  but  there  is  at  this  time,  perhaps,  not 
one  in  existence  in  this  country.  In  most  large 
factories  there  are  two  of  these  three-roller  mills  and 
in  some  three.  The  rollers  are  so  arranged  that  two 
are  placed  on  a  level  and  geared  to  move  in  the  same 
direction  while  the  third  moves  in  the  opposite  direc- 
tion. If  a  factory  operates  two  mills,  the  rollers  of  the 
first  are  farther  apart  than  those  of  the  second,  and  if 
three  mills,  the  third  has  its  rollers  closer  together 
than  the  second.  These  rollers  revolve  very  slowly 
(one  and  a  half  to  two  and  a  half  revolutions  per  min- 
ute) and  are  operated  under  great  pressure.  To  re- 
lieve the  strain  upon  the  mill,  a  cane  crusher  or 
shredder  has  come  into  general  use.  The  cane  enters 
one  of  these  as  it  leaves  the  cane  carrier  and  is  either 
crushed  or  shredded  into  small  pieces  before  reach- 
ing the  mill.  This  not  only  relieves  the  mill  of  the  work 
of  crushing  the  whole  cane,  but  increases  its  capacity. 
The  capacity  of  mills  will  vary  from  200  to  1,400  tons 
of  cane  per  day  and  the  extraction  is  70-80  per  cent 
of  the  weight  of  cane  and  90-95  per  cent  of  the  sugar 
in  the  cane.  Between  the  first  and  second  mill  the 
juice  receives  a  spray,  through  a  perforated  pipe,  of 
either  hot  or  cold  water,  the  object  being  to  dilute  the 
sugar  so  that  a  large  percentage  will  be  crushed  out 
by  the  second  mill.    This  addition  of  water  is  termed 

[189] 


10  Field  Museum  of  Natural  History 

maceration,  and  the  quantity  of  water  added  may  vary 
from  5  to  15  per  cent  of  the  weight  of  the  cane  and  in 
some  cases  as  much  as  20  per  cent,  the  quantity  de- 
pending somewhat  upon  the  value  of  fuel  and  the 
capacity  of  the  evaporating  outfit.  In  some  instances 
the  diluted  juice  from  the  third  mill  is  returned  and 
used  for  macerating  the  crushed  cane  between  the 
first  and  second  mill,  and  water  is  used  between  the 
second  and  third. 

Diffusion  has  been  practiced  at  several  factories  in 
Louisiana  and  some  other  countries,  but  it  has  not  yet 
met  with  very  great  favor. 

Purification  of  the  juice. — The  juice  as  extracted 
by  the  mill  has  a  gray  or  dark-green  color,  an  acid 
reaction,  and  contains  sucrose,  glucose,  perhaps  a  little 
levulose,  gum,  protein,  organic  acids,  pectin,  ash  or 
mineral  constituents,  soil,  coloring  matter,  fine  par- 
ticles of  suspended  cane,  etc. 

Primitive  methods  for  purifying  the  juice  do  not 
differ  essentially  from  the  practice  of  today.  The 
juice  extracted  in  crude  mills  was  heated  in  an  iron 
vessel  over  a  wood  fire.  Ashes  from  the  fire  were 
added  to  the  hot  juice.  A  dark  scum  was  thus  caused 
to  form  and  was  removed.  The  juice  was  concentrated 
by  boiling  to  a  thick  syrup  and  slowly  cooled.  This 
practice  is  still  employed  in  China  and  India.  The 
chemical  action  of  wood  ashes  is  now  easily  explained 
by  its  alkaline  constituent,  carbonate  of  potash,  which 
precipitates  certain  non-sugars  in  the  juice  and  forms 
a  dark  scum. 

For  large-scale  manufacture  more  economical 
methods  of  heating  the  juice  were  evolved.  Steam 
heat  was  first  employed  in  1785.  Other  alkalies  soon 
came  into  use,  for  instance,  carbonate  of  soda,  which  is 
used  in  India  to  the  present  day.    The  cheaper  alkali, 

[190] 


Sugar  and  Sugar-Making 


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slaked  lime,  was  first  employed  in  addition  to  wood 
ashes  in  1750  and  finally  substituted  for  it. 

In  the  modern  factory,  the  object  of  the  chemical 
treatment  is  threefold: 

1.  Clarification  by  the  precipitation  of  dissolved 
non-sugars. 

2.  Defecation  or  the  separation  of  insoluble  solid 
matter  which  has  not  been  removed  by  the  filter  but 
remains  suspended  in  the  juice. 

3.  Refining.  This  treatment  is  only  adopted  in 
the  manufacture  of  white  and  yellow  sugars  intended 
for  direct  consumption. 

The  purpose  of  clarification  is  to  remove  the  im- 
purities as  far  as  possible.  This  is  accomplished  by 
chemicals  and  heat,  causing  the  soluble  impurities  to 
become  insoluble  so  that  they  may  be  removed  by 
settling  or  filtration.  The  principal  chemicals  are 
sulphur,  lime,  and  phosphoric  acid.  Sulphur  is  ap- 
plied as  sulphur  dioxide  which  bleaches,  disinfects, 
and  coagulates  some  of  the  protein  and  prepares  the 
juice  for  taking  more  lime,  thereby  causing  a  heavier 
precipitation  which  brings  about  a  mechanical  cleans- 
ing. Sulphur  is  not  much  used  in  the  tropical  coun- 
tries where  the  juice  is  of  a  high  degree  of  purity,  but 
it  is  extensively  used  in  Louisiana  and  other  sections 
where  the  juice  contains  large  portions  of  impurities. 
Lime  is  universally  used  and  is  the  most  important  of 
all  the  chemicals  employed  in  a  sugar  factory.  It 
neutralizes  acids,  acts  upon  the  gums,  protein  sub- 
stances, coloring  matters,  and,  if  added  in  excess,  upon 
the  glucose,  converting  it  into  organic  acids.  The  lime 
compounds  thus  formed  are  largely  insoluble,  the  in- 
soluble portion  is  removed  by  settling  or  filtration  and 
much  of  the  soluble  can  be  gotten  rid  of  by  the  addi- 
tion of  phosphoric  acid  or  sodium  carbonate,  to  form 
the  insoluble  lime  salts.    Phosphoric  acid  is  also  used 

[192] 


Sugar  and  Sugar-Making  13 

to  correct  any  alkalinity  resulting  from  excessive  lim- 
ing, and  sodium  carbonate  is  very  essential  in  prop- 
erly correcting  the  acidity  of  sour  juices.  Lime  salts, 
if  left  in  solution  in  any  considerable  quantity,  give 
trouble  by  depositing  on  the  coils  of  the  "effects"  and 
"pans,"  thereby  reducing  their  efficiency  in  the  evapo- 
ration. Carbon  dioxide  is  used  to  correct  alkalinity 
and  remove  excess  of  lime. 

To  carry  out  the  process  of  clarification,  the  juice 
is  strained  through  a  copper-wire  gauze  as  it  leaves 
the  mill,  then  drawn  into  a  sulphur  box  or  tank,  if 
sulphur  is  used,  where  it  is  thoroughly  mixed  with 
sulphur  dioxide  which  is  produced  by  the  burning  of 
sulphur  in  an  appropriate  oven  near  by.  From  the 
sulphuring  apparatus  which  may  consist  of  a  box  in 
which  the  juice  and  "sulphur  gas"  are  mixed  by  a 
pump,  or  of  a  cylindrical  rotating  and  inclined  vessel 
in  which  the  mixing  takes  place  by  rotation,  the  juice 
is  drawn  into  measuring  tanks.  The  clarifiers  are 
large  rectangular  or  circular  metallic  pans,  provided 
with  a  steam  coil.  In  some  cases  the  juice  is  heated  be- 
fore entering  the  clarifiers,  in  others  it  is  heated  in 
them.  Milk  of  lime,  prepared  by  slaking  and  grinding, 
is  added  to  the  juice  in  the  clarifiers  in  sufficient  quan- 
tity to  neutralize  it,  or  leave  it  slightly  acid  or  alkaline. 
This  is  done  in  accordance  with  the  practice  of  the 
factory,  acid  juices  being  worked  to  produce  high- 
grade  sugar  and  alkaline  or  neutral  to  produce  low 
grades.  On  heating  the  limed  juice  a  portion  of  the 
impurities  rise  to  the  surface,  while  others  fall  to  the 
bottom.  It  is  the  custom  in  some  factories  to  filter 
through  heavy  canvas  bags  (one  folded  within  an- 
other) the  entire  volume  of  juice,  that  is,  the  partial- 
ly clarified  juice,  the  muddy  portion  being  conveyed 
to  filter  presses,  arranged  with  cloths  that  fit  in  be- 
tween cast-iron  plates.    The  juice  is  pumped  into  the 

[193] 


Sugar  and  Sugar-Making  15 

filter  press  where  these  cloths  retain  all  the  solid 
particles.  In  recent  years  there  has  been  added  to 
the  ordinary  process  a  super-heating  apparatus  by 
which  some  of  the  soluble  material  is  converted  into 
insoluble  material  at  a  temperature  15-30°  Fahrenheit 
above  boiling. 

Evaporization  and  crystallization. — The  evapora- 
tion of  sugar  solutions  or  cane  juice  has  for  its  object 
a  concentration  of  the  liquid  to  such  density  as  will 
cause  the  sugar  to  crystallize  out.  To  accomplish  this 
there  are  two  methods,  the  "open  kettle"  and  the 
vacuum  pan.  The  open-kettle  process  consists  in  boil- 
ing the  juice  in  open  pans,  either  of  circular  or  rec- 
tangular form,  provided  with  steam  coils.  The  heat 
is  continued  until  the  density  indicates  sufficient  cook- 
ing. When  a  density  of  22°  or  36°  Baume  is  reached, 
the  liquid  is  termed  a  syrup,  and  when  the  syrup  is 
cooked  to  a  stiff  mass,  massecuite.  After  allowing 
crystallization  to  take  place  in  wood  or  iron  vats,  the 
massecuite  is  thrown  into  a  hogshead  and  the  molasses 
percolates  through  a  perforated  bottom,  or  the  sugar 
and  molasses  may  be  separated  in  a  centrifugal  ma- 
chine. The  sugar  thus  made  is  termed  open  kettle, 
and  the  process  is  not  used  in  the  up-to-date  factory. 

The  vacuum  apparatus  for  evaporating  sugar 
solutions  consists  of  a  dome-shaped  vessel,  provided 
with  coils  of  steam  pipes  and  requires  only  about  one- 
third  the  fuel  of  the  open-kettle  process  and  reduces 
to  a  minimum  the  loss  by  burning  or  inversion  to 
glucose  and  fructose. 

The  syrup  is  drawn  from  the  syrup  tank  into  the 
vacuum  pan  until  one,  two,  or  three  coils  are  covered, 
and  this  definite  quantity  is  heated  until  grains  of 
sugar  may  be  seen  on  withdrawing  a  sample  and 
spreading  it  on  a  piece  of  glass.  The  formation  of 
crystals  is  sometimes  brought  about  by  permitting  a 

[195] 


16  Field  Museum  of  Natural  History 

little  cold  juice  to  enter  the  pan  and  suddenly  cool  it. 
The  object  here  is  to  form  a  crop  of  "seed  crystals," 
and  the  remainder  of  the  process  has  for  its  purpose 
the  increase  in  size  of  the  crystals  to  a  desired  point. 
This  is  accomplished  by  continuing  the  boiling  and 
adding,  from  time  to  time,  small  quantities  of  the 
syrup,  taking  care  that  no  more  grains  or  crystals  are 
formed.  In  three  to  four  hours  the  pan  will  be  as  full 
as  is  convenient  to  cook  it  and  the  sugar  crystals  as 
large  as  desired.  If  very  large  crystals  are  wanted, 
as  is  sometimes  the  case  with  confectioners'  sugar,  a 
"cut"  strike  is  made.  That  is,  one-third  or  one-half 
the  sugar  in  the  pan  is  removed  and  the  remaining 
portion  is  built  up  in  the  same  manner  as  already  de- 
scribed. On  completing  the  boiling  the  second  time 
there  are  not  so  many  crystals,  but  they  are  twice  as 
large.  This  process  may  be  repeated,  but  it  is  very  ex- 
pensive. The  cooking  is  continued  until  the  concen- 
trated mass  contains  6-8  per  cent  of  water.  The 
discharging  of  the  pan  is  termed  a  "strike,"  and  the 
product  discharged,  massecuite.  This  is  conveyed  to 
a  mixer  provided  with  a  shaft  carrying  paddles  or  lin- 
gers that  keep  the  sugar  and  adhering  molasses  mixed. 
The  well-mixed  massecuite  is  next  conveyed  to  a  cen- 
trifugal machine,  made  to  revolve  1,000  to  1,200  times 
per  minute,  and  in  its  rapid  motion  the  sugar  and 
molasses  are  separated,  the  latter  being  ejected 
through  very  small  perforations,  while  the  sugar  re- 
mains in  the  basket.  The  product  thus  obtained  is 
termed  "first  sugar,"  or  "raw  sugar,"  and  is  usually 
of  96  per  cent  purity. 

The  utilization  of  bagasse. — The  cane,  after  re- 
ceiving its  final  crushing  (bagasse),  whether  passed 
through  two  or  three  mills,  contains  from  40  to  50  per 
cent  of  water  and  is,  therefore,  a  poor  fuel  if  its  value 
be  estimated  on  the  weight  of  bagasse.     Even  though 

[196] 


-       T  r 


Courtesy  of  the  United  Fruit  Co. 

CENTRIFUGAL  MACHINES  FOR  CANE  SUGAR  IN  CUBA. 


18  Field  Museum  of  Natural  History 

it  is  poor  fuel  it  is  used  as  such  for  if  allowed  to  ac- 
cumulate it  would  become  a  great  nuisance  about  the 
factory.  If  the  ash  contains  silica  and  alkalies  in  pro- 
portion to  form  a  fusible  mixture,  a  slag  will  result 
and  choke  the  furnace  by  forming  a  coating  over  the 
gratings ;  for  this  reason  the  burning  of  a  mixture  of 
bagasse  and  molasses  has  not  been  satisfactory.  Not- 
withstanding its  high  water  content,  it  supplies  about 
two-thirds  of  the  fuel  in  the  Louisiana  sugar  factory 
and  practically  all  of  it  in  the  tropical  countries  where 
the  bulk  of  fiber  is  from  2  to  3  per  cent  greater. 

Bagasse  can  also  be  made  into  paper.  The  first 
patent  for  paper  manufacture  from  bagasse  was  issued 
in  1838.  The  first  large-scale  experiment  was  carried 
on  in  Texas  in  a  sugar  factory.  This  was  a  commercial 
failure  and  was  abandoned.  The  experiments  on  the 
Tacarigua  Estate,  Trinidad,  were  more  successful. 
There  bagasse  was  mixed  with  bamboo  and  Para  grass 
and  made  into  paper.  The  manufacture  of  this  paper 
was  carried  on  in  1915  by  a  sugar  factory  in  Cuba.  Im- 
provements in  the  process  have  resulted  in  the  making 
of  "wall  board"  and  paper  suitable  for  newspaper 
and  better  grades  of  wrapping  paper. 

BEET   SUGAR 

Sugar  was  noticed  in  the  ordinary  beet  in  1590  by 
Oliver  des  Serres,  but  received  no  further  attention  as 
a  source  of  sugar  until  Margraff,  a  member  of  the 
Berlin  Academy  of  Science,  in  1747,  conducted  an  in- 
vestigation of  the  sugar  content  of  various  plants. 
The  sugar  content  of  the  common  garden  beet  is  very 
small,  being  from  2  to  4  per  cent.  The  sugar  beet  is 
a  variety  of  this  derived  by  selection  and  cultivation 
from  the  wild  beet  of  the  coast  of  Europe. 

Great  interest  in  both  Germany  and  France  fol- 
lowed the  investigation  of  Achard  in   1799  and  by 

[  198  ] 


Sugar  and  Sugar-Making  19 

1812  there  were  many  factories  established.  Napoleon 
added  greatly  to  the  progress  of  this  industry  by  gov- 
ernment aid  and  by  the  establishment  of  sugar  schools. 
After  the  new  industry  had  become  well  established, 
it  was  almost  obliterated  by  destructive  wars.  It  was, 
however,  soon  revived  in  France  and  by  1829  a  yield 
of  4,000  tons  of  sugar  was  made,  but  Germany's  in- 
terest was  not  resumed  until  1835.  From  these  coun- 
tries the  industry  has  spread  throughout  Europe  until 
the  production  for  1924-25  has  been  estimated  at 
8,957,289  short  tons  for  the  world  of  which  the  United 
States  produced  1,172,000. 

The  first  experiments  with  sugar  beets  in  the 
United  States  were  made  by  two  Philadelphians  in 
1830.  About  ten  years  later  David  Lee  Child,  North- 
ampton, Massachusetts,  attempted  beet  culture  and 
the  manufacture  of  beet  sugar.  He  produced  1,300 
pounds  at  a  cost  of  eleven  cents  per  pound.  These  en- 
terprises failed  and  seem  to  have  discouraged  fur- 
ther efforts  until  Gennert  Brothers,  natives  of  Bruns- 
wick, Germany,  inaugurated  a  plant  at  Chatsworth, 
Illinois,  in  1863,  which  failed,  and  it  may  be  said  that 
this  industry  was  not  permanently  established  until 
between  1875  and  1880.  From  this  time  sugar  beet 
culture  has  been  successfully  conducted  in  the  United 
States. 

Extraction. — The  beets  are  first  washed  in  tanks. 
From  the  washing  tanks,  the  beets  are  carried  to  a 
slicing  machine,  where  they  are  cut  into  very  thin, 
narrow  pieces  so  that  when  the  chips  fall  they  will  not 
lie  too  compactly  one  upon  the  other.  The  chips  are 
conveyed  from  the  slicing  machine  to  a  hopper  feeding 
a  battery  of  twelve  to  fourteen  cast-iron  cylindrical 
cells  connected  with  each  other  by  a  system  of  pipes 
with  cocks  between,  so  that  one  may  empty  and  fill 
without  interfering  with  the  operation  of  the  rest. 

[199] 


Sugar  and  Sugar-Making  21 

The  extraction  of  the  sugar  consists  in  washing  the 
chipped  beets  with  hot  water.  When  the  sugar  has 
been  extracted  from  the  beets,  the  bottom  of  the  cell 
is  opened  and  the  beets  discharged  and  led  to  a  press 
where  most  of  the  remaining  water  and  sugar  are 
pressed  out.  The  pulp  cake  is  used  in  the  wet  condition 
for  cattle  food  or  it  may  be  dried  by  means  of  the  ex- 
haust steam  so  it  can  be  preserved  for  the  same  pur- 
pose.   It  may  also  be  used  as  a  fertilizer. 

The  purification  of  the  extracted  sugar  solution 
consists  of  the  application  of  lime,  carbon  dioxide,  and 
sulphur,  together  with  settling  and  filtering.  The  use 
of  the  lime  followed  by  carbon  dioxide  is  termed 
carbonation.  These  two  materials,  lime  and  carbon 
dioxide,  are  obtained  by  burning  limestone  in  a  kiln 
constructed  for  that  purpose  at  the  factory.  The 
limestone  is  decomposed  and  the  lime,  mixed  with 
water,  is  added  to  the  sugar  solution  in  a  quantity 
equal  to  2  or  3  per  cent.  The  gas  is  led  from  the  lime 
kiln  through  water  to  wash  it  and  admitted  into  a 
large  cell  provided  with  coils  of  steam  pipes  so  the 
solution  may  be  heated.  The  temperature  at  which 
the  carbonation  is  carried  on  is  176-94°  Fahrenheit. 
This  process  of  adding  lime,  then  charging  with  car- 
bon dioxide,  is  repeated  two  or  three  times,  depending 
upon  the  quality  of  the  juice,  but  after  the  first  treat- 
ment the  juice  is  filtered  each  time  before  repeating 
the  carbonation.  Finally  the  juice  is  treated  with 
sulphur  dioxide,  which  is  used  to  bleach  the  solution, 
and  then  the  excess  of  this  gas  or  acid  is  removed  by 
the  addition  of  lime  and  the  juice  is  again  treated  with 
carbon  dioxide.  Before  filtering,  the  juice  is  allowed 
to  settle  so  that  the  impurities  may  collect  at  the 
bottom  of  the  settling  tank.  The  clear  liquid  is  drawn 
off  and  filtered  through  bags.  The  clarified  juice  is 
treated  the  same  as  that  of  cane  sugar. 

[201] 


22  Field  Museum  of  Natural  History 

The  molasses  containing  40-50  per  cent  of  sugar, 
discharged  by  the  centrifugal,  must  be  treated  for  the 
sugar  which  it  contains,  though  some  of  the  cane 
sugar  molasses  is  sold  to  merchants  for  direct  con- 
sumption as  table  molasses,  or  to  confectioners  and  to 
glucose  mixers  for  the  preparation  of  glucose  syrup. 
Generally,  this  molasses  is  recooked  over  and  over 
again  until  all  of  the  crystallizable  sugar  has  been 
separated.  The  first  reboiling  yields  "second  sugar" 
and  "second  molasses,"  the  second  reboiling  "third 
sugar"  and  "third  molasses,"  etc.  The  massecuite  is 
returned  to  the  centrifugal,  and  the  crystals  separated 
from  the  molasses.  The  second  sugar  may  be  sold 
to  the  refineries,  but  as  it  falls  below  the  96  per  cent 
sugar  (probably  the  most  profitable  grade),  it  is  melt- 
ed in  hot  sugar  juice  and  turned  out  as  first  sugar. 
The  second  molasses  is  reboiled  to  "string  proof,"  put 
into  large  tanks  and  allowed  to  remain  at  rest  from 
four  to  six  months,  when  the  crystallized  mass  is  sub- 
jected to  centrifuging.  The  third  molasses  usually 
contains  a  large  portion  of  impurities  which  may  make 
it  unprofitable  to  reboil  it  further,  though  some  work 
this  molasses  for  fourth  sugar.  All  of  the  foregoing 
grades  of  sugar  recovered  by  reboiling  may  be  worked 
back  into  a  first  sugar  or  sold  to  the  refineries. 

The  refuse  or  exhausted  molasses,  which  amounts 
to  from  four  to  five  gallons  per  ton  of  cane  and  carries 
25-40  per  cent  sugar,  has  increased  very  much  in 
value  in  recent  years,  selling  at  six  to  ten  cents  per 
gallon.  Some  of  it  is  fed  to  stock  and  some  consumed 
by  distillers. 

REFINING  OF  CANE  AND  BEET  SUGAR 

White-sugar  loaves  were  first  manufactured  from 
cane  sugar  many  centuries  before  the  introduction  of 
the  present  refining  process  which  was  probably  de- 

[202] 


Sugar  and  Sugar-Making  23 

rived  from  the  Arabs.  Boiled  sap  was  allowed  to 
crystallize  in  conical  molds,  and  the  mother-liquor 
drained  through  a  hole  in  the  point.  Such  sugar 
loaves  were  first  imported  to  Great  Britain  in  1319, 
and  appeared  at  the  coronation  banquet  of  Henry  V  in 
1413. 

In  1812  Howard,  the  inventor  of  the  vacuum  pan, 
patented  the  use  of  saturated  sugar  solutions  for 
washing  the  sugar  loaves  in  place  of  the  old  process  of 
claying.  Purification  by  recrystallization  was  adopt- 
ed as  early  as  the  thirteenth  century.  Some  of  these 
recrystallized  loaves  were  exported  from  Cypress, 
Rhodes,  Syria,  and  Alexandria  between  1250  and 
1400.  The  present  system  of  refining  is  based  on  this 
principle,  but  with  the  addition  of  a  decolorizing  proc- 
ess applied  to  the  solution  of  raw  sugar  before  re- 
crystallization.  The  bleaching  agent — bone  char — first 
used  for  decolorizing  vinegar  in  1810  was  later  ap- 
plied to  sugar.  The  next  improvement  was  carbona- 
tion  which  the  cane  sugar  refiners  borrowed  from  the 
beet  sugar  manufacturers. 

COMPARISON  OF  CANE  AND  BEET  SUGAR 

No  one  can  distinguish  between  highly  refined 
cane  and  beet  sugar,  as  they  are  one  and  the  same 
thing.  Between  the  crude  or  raw  beet  and  cane  sugar 
there  is  a  great  difference,  the  latter  being  edible 
whereas  the  former  is  not,  as  it  possesses  a  very 
disagreeable  odor  and  taste.  Cane  sugar  molasses 
is  good  for  culinary  purposes,  beet  sugar  molasses  is 
unsuitable. 

MAPLE   SUGAR' 

Maple  sugar  production  is  an  industry  almost  en- 
tirely confined  to  Northeastern  North  America.    The 

'Other  deciduous  trees  have  been  tapped  for  sugar.  The 
butternuts  and  birches  were  made  use  of  in  this  way  by  some 
of  the  early  American  colonists. 

[203] 


24  Field  Museum  of  Natural  History 

manufacture  of  this  sugar  was  known  to  the  Indians, 
for  Jeffreys,  1760,  says  that  in  Canada  "this  tree  af- 
fords great  quantities  of  a  cooling  and  wholesome 
liquor  from  which  they  make  a  sort  of  sugar,"  and 
Jonathan  Carver,  in  1784,  says  the  Nandowessie  In- 
dians of  the  West  "consume  the  sugar  which  they  have 
extracted  from  the  maple  tree."  In  1870,  the  Winne- 
bagoes  and  Chippewas  are  said  to  often  sell  to  the 
Northwest  Fur  Company  15,000  pounds  of  sugar  a 
year.  The  sugar  season  among  the  Indians  is  a  sort 
of  carnival,  and  boiling  candy  and  pouring  it  out  on 
the  snow  to  cool  is  the  pastime  of  the  children. 

The  following  paragraph  is  from  a  book  written 
by  the  eminent  Robert  Boyle  (the  discoverer  of  Boyle's 
Law)  and  printed  at  Oxford  in  1663: 

There  is  in  some  parts  of  New  England  a  kind  of  tree  . . . 
. . .  whose  juice  that  weeps  out  of  its  incisions,  if  it  be  permitted 
slowly  to  exhale  away  the  superfluous  moisture,  doth  congeal 
into  a  sweet  and  saccharin  substance,  and  the  like  was  con- 
firmed to  me  by  the  agent  of  the  great  and  populous  colony  of 
Massachusetts. 

Maple  sap  contains  2-6  per  cent  of  sugar  and  aver- 
ages about  3  per  cent.  Eighty  to  90  per  cent  of  all 
maple  sugar  is  made  from  the  sap  of  four  species: 
the  sugar  maple  (Acer  saccharum),  the  black  maple 
(Acer  nigrum),  the  red  maple  (Acer  rubrum),  and 
the  silver  maple  (Acer  saccharinum) . 

From  nine  to  fifty-seven  days  of  the  year  are  used 
in  gathering  maple  sap  with  an  average  of  thirty- 
four  days  per  year.  The  season  lasts  from  the  middle 
of  March  to  the  middle  of  April  from  Vermont  to 
New  York.  In  Ohio  and  western  New  York  it  extends 
from  late  February  to  early  April. 

The  yield  of  sap  varies  considerably  with  the  sea- 
son, size  of  tree,  character  of  tapping,  and  many  other 
conditions.    A  tree  averages  a  yield  of  three  pounds 

T204] 


26  Field  Museum  of  Natural  History 

of  sugar  per  season  and  may  vary  from  one  to  seven 
pounds  per  tree.  From  five  to  forty  gallons  of  sap 
may  be  had  yearly  from  each  tree.  Thirty-two  gal- 
lons of  sap  are  made  into  one  gallon  of  syrup  and  four 
and  a  quarter  gallons  of  sap  contain  one  pound  of 
sugar. 

To  make  the  sugar,  the  syrup  is  heated  until  it  is 
so  thick  that  it  pours  slowly  or  becomes  waxy  in  the 
snow  or  in  cold  water  or  reaches  a  temperature  of 
230°  Fahrenheit.  It  is  then  poured  into  molds.  The 
first  run  of  sap  always  makes  the  best  sugar  and  the 
last  of  the  season  sometimes  fails  to  "cake."  During 
the  heating,  scum  is  taken  off  the  surface  by  skim- 
ming; the  sap  gradually  turns  to  an  amber  color  as 
it  reaches  the  syrupy  stage  and  deposits  malate  of  lime 
(called  "niter"  in  Vermont  and  "silica"  in  Ohio) . 

In  1860  the  total  production  of  maple  sugar  and 
syrup  in  the  United  States  reached  its  height.  It  fell 
heavily  in  1870,  arose  again  to  large  proportions  in 
1880,  remained  stationary  in  1890,  and  then  suddenly 
fell  almost  50  per  cent  in  1900,  when  the  total  amount 
produced  was  nearly  one-third  less  than  in  1850.  The 
quantity  produced  in  1923  was  about  one-half  that  of 
1900  and  amounted  to  4,685,000  pounds  of  sugar  and 
3,605,000  gallons  of  syrup.  This  reduction  has  been 
caused  in  part  by  the  felling  of  the  trees  for  lumber, 
etc.,  insect  attacks,  adulteration,  and  the  decrease  in 
the  price  of  cane  sugar. 

COMPARISON  OF  CANE  AND  MAPLE  SUGAR 
By  1875  cane  sugar  became  cheap  enough  to 
undersell  that  of  maple.  Since  1885  maple  sugar  has 
been  a  luxury  only.  In  this  capacity  its  prospects  are 
much  better  than  formerly  although  the  adulteration 
of  maple  syrup  with  glucose  and  cane  sugar  has  tended 
to  keep  down  the  price  of  maple  sugar. 

[206] 


Sugar  and  Sugar-Making  27 

SORGHUM   SUGAR 

The  stem  of  the  Guinea  corn,  or  sorghum  (Sorg- 
hum saccharatum) ,  has  long  been  known  in  China  as 
a  source  of  sugar.  The  sorghum  is  hardier  than  the 
sugar  cane;  it  comes  to  maturity  in  a  season;  and  it 
retains  its  maximum  sugar  content  a  considerable 
time,  giving  opportunity  for  leisurely  harvesting. 
The  sugar  is  obtained  by  the  same  method  as  cane 
sugar. 

Many  experiments  have  been  made  to  produce 
sugar  from  sorghum  on  a  commercial  scale  but  the  re- 
sults have  not  been  profitable.  There  is  now  very  little, 
if  any,  sugar  made  from  sorghum,  although  there  is 
considerable  syrup. 

PALM  SUGAR 

Palm  sugar  which  comes  into  the  European  markets 
as  jaggery  or  khaur  is  obtained  from  the  sap  of  sev- 
eral palms,  the  wild  date  (Phoenix  sylvestris) ,  the 
palmyra  (Borassus  flabellifer) ,  the  cocoanut  (Cocos 
nucifera) ,  the  gomuti  (Arenga  saccharif era) ,  and 
others. 

The  palm  sugar  industry  of  India  is  a  very  old 
one,  but  insignificant  compared  with  the  sugar-cane 
industry  of  that  country.  A  fair  estimate  places  the 
annual  production  of  Indian  palm  sugar  at  about 
100,000  tons. 

The  sap  of  the  palmyra  and  cocoanut  palms  is  ob- 
tained from  their  young  flowering  branches.  These 
palms  do  not  bloom  until  they  are  from  twelve  to  fif- 
teen years  old.  The  sugar-gathering  season  which  lasts 
for  several  months  commences  with  the  appearance  of 
these  branches  or  spadices  in  November  or  December. 
The  spathes  are  bruised  and  cut,  and  their  juice  or 
toddy  caught  in  a  suspended  chatty  or  toddy  receiver. 
A  spadix  continues  to  give  toddy  for  about  five  months, 

[207] 


Sugar  and  Sugar-Making  29 

at  the  rate  of  three  or  four  quarts  a  day.  Seldom  more 
than  three  spadices  yield  toddy  on  the  cocoanut  tree 
at  the  same  time,  but  seven  or  eight  will  yield  juice  at 
once  on  the  palmyra  palm.  An  expert  climber  can 
draw  toddy  from  about  forty  trees  in  a  few  hours.  It 
is  said  that  if  the  operation  be  repeated  on  the  same 
tree  for  three  successive  years,  without  allowing  any 
of  the  buds  to  bloom,  the  tree  will  die. 

To  obtain  sugar  from  the  sap,  the  "toddy"  is 
boiled  until  it  becomes  a  thick  syrup.  It  may  then  be 
poured  into  small  baskets  of  palmyra  leaf  to  cool  and 
harden  into  "jaggery,"  or  it  is  formed  into  round  cakes 
and  wrapped  in  pieces  of  dried  banana  leaves.  About 
three  quarts  of  toddy  are  sufficient  to  make  one  pound 
of  crude  sugar  or  jaggery. 

Other  palms  of  which  the  juice  of  the  spadices 
is  a  source  of  sugar  are:  the  fish-tail  palm  (Caryota 
urens),  the  gomuti  palm  (Arenga  saccharifera) ,  and 
the  African  oil  palm  (Elaeis  guineensis). 

The  wild  date  palm  (Phoenix  sylvestris)  is  tapped 
for  its  sap  as  a  source  of  sugar  quite  similarly 
to  the  maple  tree.  In  many  localities,  especially  in 
Jessore  and  other  districts  of  Bengal,  the  wild  date 
palm  is  of  importance  in  this  regard.  In  1889,  some 
168,262  acres  were  under  cultivation  here.  The  fol- 
lowing account  of  the  process  of  tapping  the  trees 
and  of  the  manufacture  of  sugar  from  the  sap  comes 
from  Sir  James  Westland. 

When  the  tree  becomes  six  or  seven  years  old 
tapping  begins  and  is  continued  each  year  there- 
after. When  the  rainy  season  has  completely  passed, 
the  cultivator  cuts  off  the  lateral  leaves  of  one-half 
of  the  circumference,  and  in  this  manner  leaves  bare 
a  surface  measuring  about  10  or  12  inches  square. 

After  the  tree  has  remained  in  this  condition  for 
a  few  days,  the  tapping  is  performed  by  making  a  cut 

[209] 


30  Field  Museum  of  Natural  History 

into  this  exposed  surface,  in  the  shape  of  a  very  broad 
V,  about  three  inches  wide  and  a  quarter  or  half  inch 
deep.  Then  the  portion  inside  the  angle  of  the  V  is 
cut  deeper,  so  that  a  triangular  surface  is  cut  into  the 
tree.  From  this  the  sap  exudes.  Caught  by  the  sides 
of  the  V,  it  runs  down  to  the  angle,  where  a  bamboo 
of  the  size  of  a  lead  pencil  is  inserted  in  the  tree  to 
catch  the  dropping  sap  and  carry  it  out  as  by  a  spout. 
The  tapping  is  arranged  throughout  the  season 
in  periods  of  six  days  each.  On  the  first  evening  a 
cut  is  made  as  just  described,  and  the  juice  is  al- 
lowed to  run  during  the  night.  This  juice  is  the 
strongest  and  best,  and  is  called  jiran  juice.  In  the 
morning  the  juice  collected  in  a  pot  hanging  beneath 
the  bamboo  spout  is  removed.  The  flow  of  juice  stops 
during  the  day.  So  in  the  evening  a  new  cut  is  made, 
not  nearly  as  deep  as  the  last,  but  rather  a  mere  par- 
ing, and  for  a  second  night  the  juice  is  allowed  to  run. 
This  juice  is  termed  do-kat  and  is  not  quite  so  abund- 
ant or  so  good  as  the  jiran.  The  third  night  no  new 
cutting  is  made,  but  the  exuding  surface  is  merely 
made  quite  clean,  and  the  juice  which  then  runs  is 
called  jarra.  It  is  still  less  abundant  and  less  rich 
than  the  do-kat,  and  toward  the  end  of  the  season, 
when  the  weather  is  getting  hot,  it  is  unfit  even  for 
sugar  manufacture,  the  gur  (molasses)  made  from  it 
being  sold  simply  as  "droppings."  These  three  nights 
are  the  periods  of  activity  in  the  tree,  and  after  these 
three  it  is  allowed  to  remain  for  three  nights  at  rest, 
when  the  same  process  is  repeated.  Of  course, 
every  tree  in  the  same  grove  does  not  run  in  the  same 
cycle,  some  are  at  their  first,  some  at  their  second 
night,  and  so  on;  and  thus  the  owner  is  always  busy. 
Since  every  sixth  day  a  new  cut  is  made  over  the 
previous  one,  the  tree  gets  more  and  more  hewed  into 
as  the  season  progresses,  and  toward  the  end  of  the 

[210] 


Sugar  and  Sugar-Making  31 

season  the  exuding  surface  may  be,  and  often  is,  as 
much  as  four  inches  deep.  The  cuts  during  the  whole 
of  one  season  are  made  about  the  same  place,  but  in 
alternate  seasons  alternate  sides  of  the  tree  are  used 
for  the  tapping;  and  as  each  season's  cutting  is  thus 
above  the  previous  season's  and  on  the  opposite  side, 
the  stem  of  the  tree  has  a  curious  zigzag  appearance. 
The  age  of  a  tree  can  of  course  be  at  once  counted  up 
by  enumerating  the  notches  and  adding  six  or  seven, 
the  number  of  years  passed  before  the  first  year's 
notch.  More  than  forty  notches  have  been  counted  on 
a  tree,  but  one  rarely  sees  them  so  old.  When  they  are 
forty-six  years  old  they  are  worth  little  as  sugar-pro- 
ducing trees.  It  is  somewhat  remarkable  that  the 
notches  are  almost  always  on  the  east  and  west  sides 
of  the  tree  and  very  rarely  on  the  north  and  south 
sides;  also  that  the  first  notch  appears  to  be  made  on 
the  east  side  in  by  far  the  majority  of  instances. 

One  may  expect  from  a  good  tree  a  regular  aver- 
age of  five  pints  of  sap  per  night  (excluding  the 
quiescent  nights) .  The  colder  and  clearer  the  weather, 
the  more  copious  and  rich  the  juice.  In  the  beginning 
of  November  tapping  begins.  In  December  and  Jan- 
uary the  juice  flows  best,  beginning  sometimes  as  early 
as  3  P.M.,  and  decreasing  with  the  coming  of  the  warm 
days  of  March.  If  the  cultivator  begins  too  early,  or 
continues  too  late,  he  will  lose  in  quality  and  quantity 
as  much  as  he  will  gain  by  extending  the  tapping 
season. 

The  next  process  is  the  boiling,  and  this  every 
rayat  does  for  himself,  and  usually  within  the  limits 
of  the  grove.  Without  boiling,  the  juice  speedily 
ferments  and  becomes  useless;  but  once  boiled  down 
into  gur,  it  may  be  kept  for  very  long  periods.  The 
juice  which  was  at  first  brilliant  and  limpid,  becomes 
now  a  dark-brown,  half-viscid,  half-solid  mass,  and 

[211] 


32  Field  Museum  of  Natural  History 

when  it  is  still  warm,  it  is  easily  poured  from  the 
boiling-pan  into  the  earthenware  pots  in  which  it  is 
ordinarily  kept.  As  it  takes  from  seven  to  ten  pints 
of  juice  to  produce  one  pint  of  gur  or  molasses,  one 
can  calculate  the  amount  of  gur  which  a  good  tree  can 
produce  in  a  season.  One  may  count  four  and  a  half 
months  for  the  tapping  season,  or  about  sixty-seven 
tapping  nights.  These,  at  five  pints  each,  produce 
335  pints  of  juice,  which  will  give  about  forty  pounds 
of  gur. 

After  the  juice  is  boiled  down  into  gur  it  is  then 
sold  to  the  sugar-refiners  and  by  them  is  manufac- 
tured in  various  ways  into  different  grades  of  sugar. 
The  best  known  is  called  dhulva,  a  soft,  moist,  powdery 
sugar,  used  largely  in  the  manufacture  of  native  can- 
dies. Another  kind,  termed  pucka,  is  purer,  granular, 
and  more  expensive.  The  waste  molasses,  collected 
during  the  preparation  of  sugar,  is  called  chitiya  gur. 
When  boiled  for  a  longer  time,  it  becomes  a  black, 
sticky  treacle,  which  is  largely  utilized  for  mixing 
with  tobacco  for  the  native  hookah,  and  also  for  mak- 
ing cheap  candy.  A  small  proportion  of  the  juice  is 
consumed  as  a  drink  either  fermented  or  unfermented, 
under  the  name  of  tari,  or  is  converted  into  vinegar. 

OTHER  SUGARS 

Malt  sugar  preparations. — A  sweet  material  called 
"ame"  has  been  made  in  Japan  since  early  times 
from  glutinous  rice  or  glutinous  millet,  sometimes  from 
common  rice  and  rarely  from  Indian  corn  or  sweet  po- 
tatoes. Ame  is  made  from  these  by  converting  their 
starch  into  maltose  by  the  action  of  an  enzyme  called 
diastase.  Sprouted  barley  is  generally  used  to  furnish 
the  enzyme.  In  making  ame  the  grains  or  potatoes 
are  first  cleaned,  then  soaked  in  water  and  steamed 
until  the  starch  grains  are  broken  and  made  easily  ac- 

[212] 


Sugar  and  Sugar- Making  33 

cessible  to  the  enzyme.  Powdered  malt  and  water  in 
proper  proportions  are  now  added,  and  in  six  or  eight 
hours  the  diastase  converts  most  of  the  starch  into 
dextrin  and  maltose.  The  liquid  is  then  filtered  and 
evaporated  to  the  desired  consistency.  One  of  the 
forms  is  a  dense,  clear,  light-colored  amber  liquid. 
Another  form  is  hard  and  quite  similar  to  white  candy 
in  appearance.  Ame  has  been  made  in  Japan  for  at 
least  two  thousand  years,  and  long  before  cane  sugar 
was  known  it  was  a  favorite  flavoring.  Even  at  the 
present  time  it  is  sometimes  used  instead  of  sugar  in 
cooking  and  it  also  makes  a  favorite  addition  to  the 
food  of  invalids. 

Several  malt  preparations,  some  of  them  thick  like 
syrup  and  others  more  of  the  consistency  of  candy,  are 
on  the  market.  These  are  mixtures  of  dextrin  and 
maltose  coming  from  the  action  of  diastase  on  starchy 
materials.  Many  commercial  products,  such  as  those 
called  "predigested"  and  "malted,"  have  this  material 
as  their  basis. 

Glucose. — Glucose  is  manufactured  in  large 
amounts  in  the  United  States  from  corn-starch,  and  is 
sold  for  table  syrup  and  other  purposes.  It  is  prepared 
by  a  chemical  process  which  consists  of  hydrolyzing 
the  starch  into  glucose  by  means  of  dilute  acid  and 
pressure.  Frequently  part  of  the  output  of  a  glucose 
plant  is  blended  with  maple  syrup  or  other  flavoring 
material.  The  resulting  mixtures  are  palatable  and 
nutritious  but  do  not  have  the  body-heating  value  nor 
the  sweetness  of  syrups  having  the  same  percentage  of 
cane,  maple,  and  sorghum  sugar. 

Miscellaneous  sugars. — Other  sugars  which  before 
1914  were  largely  or  entirely  imported,  but  which  are 
now  made  in  the  United  States  in  amounts  sufficient 
for  local  needs,  are  lactose  (milk  sugar)  used  in  the 
preparation  of  infant  foods,  etc. ;  levulose,  used  in  place 

[213] 


34  Field  Museum  op  Natural  History 

of  cane  sugar  in  the  foods  of  persons  suffering  from 
diabetes,  etc. ;  and  the  so-called  "rare"  sugars,  such  as 
maltose,  mannose,  xylose,  melezitose,  melibiose,  treha- 
lose, rhamnose,  etc.,  used  almost  solely  in  chemical 
and  bacteriological  investigations.  The  production  of 
these  sugars  varies  from  about  6,000,000  pounds  in  the 
case  of  lactose  to  possibly  less  than  one  ounce  in  the 
case  of  some  of  the  rare  sugars,  and  the  price  varies 
from  about  twenty  cents  per  pound  in  the  case  of  lac- 
tose to  twenty-five  dollars  or  more  an  ounce  in  the  case 
of  certain  of  the  rare  sugars. 

James  B.  McNair 


Exhibits  illustrating  the  processes  of  cane  and  beet  sugar- 
making,  together  with  specimens  of  various  sugars,  are  to  be 
found  in  the  economic  exhibits  of  the  Department  of  Botany  on 
the  south  side  of  Hall  25  in  the  Museum.  The  various  palms 
mentioned  are  on  the  north  side  of  the  same  Hall.  A  flower  of 
the  "Boer  Honey  Pot"  may  be  seen  in  the  Hall  of  Plant  Life 
(Hall  29). 


[2141 


